[racket] rackunit question

Hi there,
In a small program I like to have the test cases in the same file. How
can I prevent the 'main' function of my program to be run when I do a
raco test?


Here is a minimal example:

#lang racket


(define (myfun)
  (displayln "hey"))

(myfun)


(module+ test
  
  (require rackunit)
  
  (check-equal? 1 1)
  
  "all tests run")


How can I prevent myfun from being run when I issue
   raco test mytest.rkt 
?


Is there a condition I could ask for? Something like this:
  (when (not-raco-testing?)
     (myfun))



-- 
Manfred